Turbine Outlet Pressure (TC1TOP) The TC1TOP sensor is a variable capacitance sensor

that monitors exhaust back pressure.

The sensor measures back pressure in the exhaust system. A tap for the TC1TOP is located in the exhaust, between the LP turbocharger and EBPV.

The TC1TOP sensor is located in the Air Control Valve, on the right side of the engine.

Magnetic Pickup Sensors

Figure 28 Magnetic pickup sensor example

A magnetic pickup sensor contains a permanent magnet core that is surrounded by a coil of wire.

The sensor generates a voltage signal through the collapse of a magnetic field created by a moving metal trigger. The movement of the trigger then creates Alternate Current (AC) voltage in the sensor coil.

Magnetic pickup sensors used include the following:

• CKP sensor

• CMP sensor

• VSS

• CCOSS sensor

Crankshaft Position (CKP) Sensor

The CKP sensor is a magnetic pickup sensor that indicates crankshaft speed and position.

The CKP sensor sends a pulsed signal to the Engine Control Module (ECM) as the crankshaft turns.

The CKP sensor reacts to holes drilled into the flywheel adjacent to the ring gear. For crankshaft position reference, teeth 59 and 60 are missing. By comparing the CKP signal with the CMP signal, the ECM calculates engine rpm and timing requirements.

The CKP sensor is installed in the top left of the flywheel housing.

Camshaft Position (CMP) Sensor

The CMP sensor is a magnetic pickup sensor that indicates camshaft speed and position.

The CMP sensor sends a pulsed signal to the ECM as a toothed wheel on the camshaft rotates past the CMP sensor. The ECM calculates camshaft speed and position from CMP signal frequency.

The CMP sensor is installed in the left rear of the cylinder head.

Vehicle Speed Sensor (VSS)

The VSS provides the ECM with transmission tail shaft speed by sensing the rotation of a 16-tooth gear on the rear of the transmission. The detected sine wave signal (AC) received by the ECM, is used with tire size and axle ratio to calculate vehicle speed. The VSS is located on the left side of the transmission housing for automatic transmissions, or at rear of the transmission housing for manual transmissions.

Crankcase Oil Separator Speed (CCOSS) sensor The CCOSS sensor sends the ECM information about the speed of the crankcase oil separator internal components. The detected sine wave signal (AC) received by the ECM is used to monitor proper operation of the cyclonic oil separator, located inside the breather assembly on the engine oil filter assembly.

Potentiometer Sensors

Figure 29 Potentiometer example

A potentiometer is a variable voltage divider that senses the position of a mechanical component.

A reference voltage is applied to one end of the potentiometer. Mechanical rotary or linear motion moves the wiper along the resistance material, changing voltage at each point along the resistive material. Voltage is proportional to the amount of mechanical movement.

The engine has two potentiometers, both contained in the Accelerator Pedal Position (APP) Sensor.

Accelerator Pedal Position (APP)

The APP provides the ECM with a dual feedback signal (dual linear analog voltages) that indicate the operator’s demand for power. The APP contains two potentiometers, and provides two individual signals (APP and APP2) to the ECM. The APP is installed in the cab on the accelerator pedal assembly.

Switches

Figure 30 Switch example

Switch sensors indicate position, level, or status.

They operate open or closed, regulating the flow of current. A switch sensor can be a voltage input switch or a grounding switch. A voltage input switch supplies the control module with a voltage when it is closed.

A grounding switch grounds the circuit when closed, causing a zero voltage signal. Grounding switches are usually installed in series with a current limiting resistor.

Switches include the following:

• Driveline Disengagement Switch (DDS)

• Engine Coolant Level (ECL)

• Oil Level Sensor (OLS)

Driveline Disengagement Switch (DDS)

The DDS determines if a vehicle is in gear. For manual transmissions, the clutch switch serves as the DDS. For automatic transmissions, the neutral indicator switch functions as the DDS. The DDS signal is sent to the Body Controller (BC) and transmitted on the J1939 datalink to the engine ECM.

Engine Coolant Level (ECL) Switch

The ECL switch is part of the EWPS. The ECL switch is located on the deaeration tank. When the magnetic switch is open, the tank is considered full of coolant.

If engine coolant is low, the switch closes and the red ENGINE lamp on the instrument panel is illuminated.

Oil Level Sensor (OLS)

The OLS is part of the EWPS. The OLS is located on the engine oil pan. The OLS measures the volume of oil in the oil pan and broadcast the percentage volume over J1939 CAN.

If the level of engine lube oil is low, the red ENGINE lamp on the instrument panel is illuminated.

Additional Sensors Oxygen Sensor (O2S)

The O2S monitors oxygen levels in the exhaust.

The O2S is used to control the EGR flow to a specified air-to-fuel ratio by monitoring the level of unused oxygen in the exhaust stream.

The O2S compares oxygen levels in the exhaust stream with oxygen levels in the outside air. The sensor generates an analog voltage and is monitored by the ECM. The level of voltage generated by the O2S directly corresponds to the oxygen levels in the exhaust stream.

The O2S is installed in the turbocharger exhaust pipe, directly after the EBPV.

Humidity Sensor (HS)

The HS measures the moisture content of filtered air entering the intake system.

Using the HS, the ECM will adjust in order to prevent condensation of airborne water particles (moisture).

The HS also houses the AIT sensor, which is used by the ECM for calculating fuel delivery.